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1. Dr. Rajendran. S
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2.  Blood glucose regulates insulin secretion
 Insulin regulates blood glucose
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3. 
Direct feedback effect on pancreatic beta cells
▪
When plasma glucose ↑
▪
▪
When plasma glucose ↓
▪

Insulin secretion ↑
Insulin secretion ↓
Great precision
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4. Pancreas
Blood
glucose
Insulin
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5. 
Insulin regulates blood glucose
 Glucose production by the liver
 Uptake and utilization in peripheral tissues
▪ Muscle
▪ Adipose tissue
▪ Liver
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6. 
80 to 90 mg/100 ml
 Rate of insulin secretion is low

Plasma glucose < 75 mg / dl
 Insulin secretion inhibited
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7. 
> 75 mg/dL
 Stimulate insulin synthesis and insulin secretion

Blood glucose > 100 mg/100 ml
 Insulin secretion rises rapidly
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8. 
Glucose between 300 and 500 mg / dl
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9. 

Glucose enters B cells via GLUT 2
Pancreas
 Beta cell glucose sensor
▪ Insulin independent
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14. 
Controls glucose-regulated insulin secretion
 Phosphorylation
▪ Rate-limiting step in glucose metabolism in the beta
cell and insulin release
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15. 
Incretins

GI hormones that potentiate insulin secretion

Cause 50% of the insulin released after a meal
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16. 

Glucagon Like Peptide-1 (GLP-1)
Gastric Inhibitory Peptide (GIP)
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17. 
Released from small-intestinal endocrine
cells postprandially
 Reach the beta cells through the bloodstream
▪ Increase the sensitivity of islet cells to glucose
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18. 
Insulin secretion greater after oral than
after intravenous glucose administration
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19. Glucose
Incretins
Insulin
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22. www.medicinemcq.com
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23. 



Stimulates insulin secretion
Increases beta cell mass
Inhibits glucagon secretion
Delays gastric emptying
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24. 
Raises levels of cAMP
 Activates cAMP-dependent protein kinase A
▪ Amplify the Ca2+ signal by decreasing Ca2+ uptake by
cellular stores
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25. 

Stimulates insulin secretion when glucose
levels are elevated
Decreases glucagon-stimulated hepatic
glucose production
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26. 


Amplify the glucose-induced release of
insulin from the beta-cell
Stimulate insulin release in the absence of
glucose
Most potent
 Arginine
 Lysine
 Leucine
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27. 
Amino acid metabolism and ATP
generation
 Elevated beta-cell Ca2+ concentrations
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28. 
Only minor effects on insulin release
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29. 
Promote the secretion of insulin
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30. 
Beta2
 Enhance insulin secretion

Alpha2
 Inhibits insulin release
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31. 
Suppresses the secretion of insulin
 Stimulation of alpha2 adrenergic receptors and
inhibition of insulin secretion
▪
▪
▪
▪
▪
▪
Hypoxia
Hypoglycemia
Exercise
Hypothermia
Surgery
Severe burns
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32. 
Alpha 2
 Increase basal concentrations of insulin

Beta2
 Decrease basal concentrations of insulin
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33. 
Inhibit insulin secretion
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34. 
Inhibit insulin secretion
 Through G protein–coupled receptor (GPCR)
mechanisms
▪ Inhibit adenylate cyclase
▪ Modify Ca2+ and K+ channel gating.
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35. 

Stimulates insulin secretion
Insulin inhibits glucagon secretion
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